In the past, most houses were constructed with fireplaces to provide head in almost every room. These days central heating has effectively declined the use of fireplaces, and therefore many homeowners consider removing chimney breasts as see them as a wasted floor space. Other most common reasons why people are happy to demolish chimneys are heat loss, roof leakage, damaged brickwork or regular maintenance and cleaning requirements.
What you need to know before removing a chimney breast
There are two main parts of a chimney that can be removed; the chimney breast and the stack. The stack is a visible part that protrudes above the roofline and the breast is the majority of the chimney. In other words, this is the bulky part present in rooms that the chimney breast passes through.
If you are planning on removing your chimney breast, it is important to have an adequate structural support designed by a qualified professional like our structural engineer Croydon. This is due to the fact that chimney is considered as an integral part of the house structure, and hence an adequate support documentation needs to be developed and handed over to the contractor prior commencement of any demolition works . We would strongly advice to seek a professional advice as unsupported chimney is one of the most common causes of a long-term damage to the building fabric and other structural components of the house.
Building Regulations consider chimney removal as a ‘material alteration’ to the structure, and therefore a regulated approval process would require a calculation report prepared by fully insured and qualified structural engineer like GL Design Services. Also, a planning permission for this type of work might be required depending on Local Council guidelines if property happens to be located in a conservation area.
The matter also frequently falls into the category of work under the Party Wall etc Act 1996, which means that a relevant notice needs to be served to any adjacent property owners. This is to ensure that any commonly shared parts of the house will remain structurally sound and continue serving its purpose.
Gallow brackets or steel beams as a chimney breast support?
Gallow brackets or steel beams are commonly used to support remaining part of the chimney breast, especially at loft level. Gallows brackets are a pair of triangulated metal brackets which are often branded as an ‘off-the-shelf’ chimney breast support. They usually sit beneath the remaining chimney and have a pre-cast concrete lintel atop that actually supports weight of the overlaying masonry. Steel beams are horizontal structural elements designed to carry vertical loads from the remaining chimney, and transfer reaction forces via padstone onto load bearing walls below.
Gallow brackets may seem as easy and cheap solution to install and can often be described as such to homeowners by building contractors. However, there are quite a few restrictions and pre-conditions where such support can be signed off by Building Control – a handy guide on this subject can be found on the Local Authority Building Control website. Unfortunately, in most cases Building Control view gallow brackets support as non-compliant with Building Regulations. The main concern is not with the bracket itself but load transfer mechanism that induces eccentricity into the supporting wall. Eccentrically applied loads via brackets induce a pull-out action on masonry at fixing locations, causing a structural movement. If neglected, such movement can lead to a severe wall damage and, in extreme cases, collapse of the chimney. Therefore, our structural engineer Croydon usually advises against using this type of support to preserve structural integrity and stability of traditionally built structures.
Our preferred method of a chimney support is to use steel beams to safely transfer loads onto suitable bearing walls below. Arrangement of chimney supporting beams should always be developed following a detailed inspection as there may be site constrains related to current position of access hatch, timber purlins, struts etc. Our local structural engineer should always be consulted to develop a safe solution to allow for removal of any existing chimneys.
Timber beams and corbelled brickwork are not considered satisfactory in any circumstances.
Finally, please be aware that the above information is for guidance only and all necessary statutory, legal approvals, party structure approvals, must be first obtained before carrying out any structural works. We are happy to provide a free initial advise and quotation for design work – Contact us.